Semiconductor chips or wafers are used in many applications, including as integrated circuits and as flash memory for hand held computing devices, wireless telephones, and digital cameras. A common circuit component of flash memory devices is the transistor. In these devices, a transistor is established by forming a gate stack including a control gate and a floating gate on a silicon substrate, and then forming a source region and a drain region in the substrate beneath the gate stack by implanting ion dopants into the areas of the substrate that are to become the source and drain regions. This generally-described structure cooperates to function as a transistor.
After the gate stacks have been formed, subsequent manufacturing steps are undertaken to complete the semiconductor device. These subsequent steps include, among other things, the formation of additional layers of transistors along with interlayer dielectrics (ILD), followed by metallization and external electrical contact formation. It happens, however, that during these subsequent steps, mobile ions and/or other processed-induced charges can migrate into the sides of the floating gate, which undesirably can alter an electrical characteristic of the device, such as the threshold voltage or current, from its design value. This in turn adversely affects the reliability of the transistor. The present invention recognizes this prior art drawback and provides the below-noted solutions.